Does updating iPhone hurt battery in the long run

A lot of updates might result in bookkeeping tasks being run for a short period. But long term it's really needed for all sorts of reasons - especially security updates. And of course it's a complicated product with a ton of software, and sometimes not everything is anticipated.

No "downgrade" possible.

The most "non-normal use damage" I would expect from upgrading is if you do not plug in during the process ... that generates battery cycles. But then any use of the iPhone will eventually use both CPU and battery.

Connorflippin Said:

"Does updating iPhone hurt battery in the long run: I’m always hesitant about updating my 13 Pro because every time you update it it adds more stuff and the phone has to process more stuff which uses more power which leads to bad battery life in a long run so I was wondering.[...]"

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Based on Personal Experience:

It Might (Due to a Corrupt Install):

A pure reason to get AppleCare+ with your iPhone. My Mac failed 11 times after the High Sierra Upgrade. Thank goodness I had AppleCare+ with it. So, you might want to consider the same. You have 60 days to purchase it form the date your get it in the mail or at the store. Go here for more: AppleCare Products - Apple Support